1. Field of the Invention
The present invention relates to a hydrogen generating apparatus, more particularly to a hydrogen generating apparatus that can control the amount of generation of hydrogen supplied to a fuel cell.
2. Background Art
A fuel cell refers to an energy conversion apparatus that directly converts chemical energy of a fuel (hydrogen, LNG, LPG, methanol, etc.) and air to electricity and/or heat by means of an electrochemical reaction. Unlike a conventional power generation technology that requires fuel combustion, steam generation, or a turbine or power generator, the fuel cell technology needs no combustion process or driving device, thereby boosting energy efficiency and curbing environmental problems.
FIG. 1 illustrates an operational architecture of a fuel cell.
Referring to FIG. 1, a fuel cell 100 is composed of an anode as a fuel pole 110 and a cathode as an air pole 130. The fuel pole 110 is provided with hydrogen molecules (H2), and decomposes them into hydrogen ions (H+) and electrons (e−). The hydrogen ion (H+) moves toward the air pole 130 via a membrane 120, which is an electrolyte layer. The electron moves through an external circuit 140 to generate an electric current. In the air pole 130, the hydrogen ions and the electrons are combined with oxygen molecules in the atmosphere, generating water molecules. The following chemical formulas represent the above chemical reactions occurring in the fuel cell 100.Fuel pole 110: H22H++2e−Air pole 130: ½O2+2H++2e−H20Overall reaction: H2+½O2H20  CHEMICAL FORMULA 1
In short, the fuel cell 100 functions as a battery by supplying the electric current, generated due to the flowing of the decomposed electrons, to the external circuit 140. Such a fuel cell 100 hardly emits an atmospheric pollutant such as Sox and NOx and makes little noise and vibration.
Meanwhile, in order to produce electrons in the fuel pole 110, the fuel cell 100 necessitates a hydrogen generating apparatus that can change a common fuel to hydrogen gas.
A hydrogen storage tank, generally known as a hydrogen generating apparatus, however, occupies a large space and should be kept with care.
Moreover, as a portable electronic device, such as a mobile phone and a notebook computer, requires a large capacity of power, it is necessary that the fuel cell have a large capacity and perform high performance while it is small.
In order to meet the above needs, methanol or formic acid, permitted to be brought into an airplane by International Civil Aviation Organization (ICAO), is used for fuel reforming, or methanol, ethanol, or formic acid is directly used as a fuel for the fuel cell.
However, the former case requires a high reforming temperature, has a complicated system, consumes driving power, and contains impurities (e.g., CO2 and CO) in addition to pure hydrogen. The latter case deteriorates power density due to a low rate of a chemical reaction in the anode and a cross-over of hydrocarbon through the membrane.